Bigsun Udaan › Finance reference guides › GST lesson 3
TDS & Tax · GST lesson 3 of 5
Tax invoice and GST calculator
See what goes on a GST invoice, how GST and TDS meet on the same bill, and practise the arithmetic.
What is on a tax invoice?
A registered business gives a tax invoice for each taxable sale. It usually shows:
- Supplier's name, address and GSTIN
- A unique invoice number and date
- Customer's name, address and GSTIN (for sales to other businesses)
- Description of goods or services, with HSN or SAC code, and quantity
- Taxable value (the price before GST)
- GST rate and amount, split as CGST + SGST or as IGST
- Place of supply, total amount, and a signature
B2B invoices generally need a 4-digit HSN code, and larger businesses need 6 digits. Services are normally invoiced within a set number of days of supply (generally 30). Confirm the current rules on the GST portal.
How GST and TDS meet on one invoice
A consultant invoices a company (fictional): fee ₹1,00,000 + 18% GST ₹18,000 = invoice total ₹1,18,000.
- Because GST is shown separately, TDS under 194J(b) at 10% is normally worked out on ₹1,00,000, giving ₹10,000.
- The company pays the consultant ₹1,18,000 − ₹10,000 = ₹1,08,000.
The ₹18,000 GST goes to the government through the consultant's GST return. The ₹10,000 TDS is the company's deposit against the consultant's income tax.
Practice calculator
For learning only. It shows how the arithmetic works. The right rate for a real product must always be taken from the official schedule.
Try these
- ₹50,000 at 18%, same state. (Answer: CGST ₹4,500 + SGST ₹4,500, total ₹59,000.)
- A final price of ₹1,180 at 18%. What was the price before GST? (Answer: ₹1,000.)
- ₹20,000 at 5%, different state.
- Write the numbers for a consultant fee of ₹60,000 + 18% GST, and the TDS at 10% on the fee.
Check yourself
1. A bill shows ₹10,000 before GST at 18%. What is the invoice total?
GST is ₹1,800, so the total is ₹11,800.
2. A final price of ₹1,180 includes 18% GST. The price before GST is…
₹1,180 ÷ 1.18 = ₹1,000.
3. On a consultant's invoice with GST shown separately, TDS is normally worked out on…
TDS is normally on the amount excluding separately shown GST.
4. Which is NOT usually part of a tax invoice?
Invoices never include bank passwords.
Learning material for beginners, checked in October 2026. It is not tax or legal advice. GST rates, limits and due dates change, and websites sometimes disagree on details. Always confirm on the GST portal (gst.gov.in) or with a Chartered Accountant or GST practitioner before applying anything in real work. All names and amounts in the examples are made up.